1. Technical Field
The present disclosure relates to a method for making anion electrolyte membranes.
2. Discussion of Related Art
Ion exchange membranes are key components for direct methanol fuel cell (DMFC), polymer electrolyte membrane fuel cell (PEMFC), and vanadium redox battery (VRB). The ion exchange membrane is a membrane having ion groups, selectively permeable for specific ions, and separating cathode electrode from anode electrode but transferring ions between the cathode electrode and the anode electrode. The ion exchange membranes should have high conductivity and selectivity for ions, high stability, and good mechanical strength. By having anion groups or cation groups, the ion exchange membrane can be an anion exchange membrane and a cation exchange membrane.
The most widely used ion exchange membranes are perfluorinated sulfonic acid membranes having sulfonic groups with negative charges.
In PEMFC and DMFC, the catalysts are nano-sized particles of platinum to endure the strong acidic circumstance caused by the perfluorinated sulfonic acid membranes. However, nano-sized platinum is expensive, which increases the costs of the fuel cells. By changing from acidic to alkaline, the cost of the fuel cells can be dramatically reduced because cheaper catalysts derived from non-noble metal such as rhodium, cobalt, nickel and silver can be used.
In VRB, the sulfonic groups of the perfluorinated sulfonic acid membranes can let proton transferred therethrough. However, the vanadium ion can also transfer through the membranes, which causes a cross pollution of the electrolyte and resulting the self-discharge of the batteries.
Further, the manufacture of the perfluorinated sulfonic acid membranes is complicated and costly.
What is needed, therefore, is to provide a method for making an anion electrolyte membrane.